It is future development trend to manufacture and use green building materials to construct green buildings in the construction field. A concept of “promoting green development, cyclic development, low-carbon development” and “Construct Wild China” was put forward by 18th CPC National Congress which was just closed. With the development of urbanization, a large number of housing which have not reached their service life are removed due to the damage of the wall insulation veneer, causing serious influence on the green development of city.
Exterior wall insulation includes single material (aerated concrete, sintered insulating brick, etc.) exterior wall insulation and composite material exterior wall insulation (interior thermal insulation, exterior thermal insulation, sandwich thermal insulation and block thermal insulation, etc.). Although there are many ways of exterior wall insulation, few of them realize an integration of decoration and insulation, and in order to meet the decoration requirement, it is necessary to construct a decorative layer on the surface of an insulation layer after construction of the insulation layer. However, since the insulation layer has been constructed on a wall, then it is very inconvenient to add a decorative layer onto the insulation layer.
After much trial and error, the applicant develops an exterior wall insulation board which realizes integration of insulation and decoration. The insulation board comprises a metal veneer and a substrate oppositely arranged with an insulation layer disposed therebetween. The applicant firstly screen prints a multicolor pattern on the metal veneer by using a screen printing machine, and then glues the metal veneer, the insulation layer and the substrate together to form the exterior wall insulation board which is finally constructed on an exterior wallbody. It provides much more convenience for processing the decorative layer, compared with the traditional way by which an insulation layer is installed firstly followed by constructing a decorative layer.
However, during the process of using the screen printing machine, the applicant found out that, in screen printing process, a certain pressure has to be applied to ink by using the scraper, accordingly the ink is capable of penetrating through some mesh of image area and forms required patterns or code bar on a substrate; and if the substrate is a paper, it will be flat when tiling on a printing table, thus printing various parts can be performed under a uniform force applied by the scraper on the ink; the substrate may also be a steel plate, and most of steel plates are hot rolled or cold rolled, and in the hot rolling or cold rolling process, the steel plate is usually changed shape, as a result the steel plate cannot be completely flattened (i.e. the steel plate is in a bent status that both ends upwarp and the center part contacts the printing table, or the center part upwarps and both ends contact the printing table), thereby the printing cannot be achieved when the scraper applies the uniform force to the substrate, which increases the difficulty of printing; more importantly, because the steel plate is unevenness, the scraper has to apply a force on the steel plate when both are in line contact, however, relying entirely on the scraper cannot ensure the flatness; in addition, the screen printing forme and the steel plate have a great strength difference, therefore, it is a technical problem of how to balance of strength difference of the screen printing forme and the steel plate.
In conclusion, when printing patterns on the steel plate by using the screen printing machine, it is an unsolved technical problem of how to overcome the printing difficulty because the steel plate is unevenness in the prior art.